A genetic and biochemical approach to regulation of adenyl cyclase in membranes is proposed. Previous experiments with the fr mutant of Neurospora, which has a linolenic acid deficiency, a defective adenyl cyclase, and a reduction of endogenous cAMP, suggested that the lipid composition of the membrane influences the in vivo functioning of the membrane bound adenyl cyclase. The goal of this project is to test this possibility by systematically monitoring, through supplementation and biochemical techniques, the fatty acid and phospholipid composition of fr and various lipid auxotrophs. By taking advantage of the unique relationship in fr between the degree of morphological abnormality and cAMP reduction, the functional significance of these manipulations on the adenyl cyclase and organism as a whole can be assessed. This information is to be applied to our understanding of the role of membrane structure in controlling various cellular processes through regulation of important membrane-associated functions such as the adenyl cyclase system.